THE SIGNIFICANCE OF CHROMOSOMAL TRANSLOCATION INVOLVING BCL6 GENE IN MALIGNANT LYMPHOMA

我们在BCL6基因中发现了两个负调控BCL6表达的区域。一个区域ES位于第一个内含子内，第二个区域is位于第一个内含子内。在ES中发现了BCL6蛋白本身结合的一致核苷酸序列。IS区包含在b细胞淋巴瘤中通常缺失的区域中，具有消音器活性。这两个区域的结构改变可能在b细胞淋巴瘤中BCL6基因的表达失调中起作用。我们报告一例来源不明的非何杰金氏淋巴瘤侵袭骨髓及脑部。利用FISH和SKY技术，我们确定了14q32易位、22q13易位的新伙伴位点，以及涉及2p23作为新供体染色体的跳跃易位。我们还可以确定t(3; 14)（q27; q32）的不平衡易位。因此，SKY和FISH结合使用14q端粒探针被认为对b细胞淋巴瘤复杂细胞遗传学病例的表征非常有用。我们以小鼠BAZF为探针克隆了原癌基因BCL6的同源基因——人BAZF基因。预测的氨基酸序列与小鼠BAZF的相同度为91%。荧光原位杂交分析显示，人BAZF基因位于染色体17p13.1上。虽然人BAZF mRNA在人体组织中普遍表达，但在心脏和胎盘中也有大量表达。BAZF mRNA在部分未成熟B细胞株和红白血病细胞株中表达。在TPA诱导的巨核细胞分化过程中，人红细胞白血病细胞系HEL细胞表达上调。

We identified two regions in the BCL6 gene that negatively regulate BCL6 expression. One region, ES, is located within the first and a second region, IS, is located within the first intron. A consensus nucleotide sequence for the binding of the BCL6 protein itself was found within the ES. The IS region which is included in the regions commonly deleted in B-cell lymphomas had a silencer activity. Structural alterations of these two regions may play roles in the deregulated expression of the BCL6 gene in B-cell lymphomas.We report a case of non-Hodgkin's lymphoma of unknown origin with invasion into bone marrow and brain. Using FISH and SKY technique, we identified the new partner site of the 14q32 translocation, 22q13, and the jumping translocations involving 2p23 as a new donor chromosome. We could also identify the unbalanced translocation of t(3 ; 14)(q27 ; q32). The combination of SKY and FISH using the 14q telomere probe was therefore considered very useful for the characterization of complex cytogenetic cases in B-cell lymphoma.We cloned the human BAZF gene, homologue of protooncogene BCL6, using murine BAZF as a probe. The predicted amino acid sequence was 91% identical to that of murine BAZF. Fluorescence in situ hybridization analysis revealed that the human BAZF gene is located on chromosome 17p13.1. Although expression of human BAZF mRNA was ubiquitously detected in human tissues, abundant expression was detected in heart and placenta. BAZF mRNA was expressed in some immature B cell lines and erythroleukemia cell lines. The expression in a human erythroleukemia cell line, HEL cells, was upregulated during megakaryocytic differentiation induced by TPA.